Electromyographic (EMG) activity at various locations on the skin surface of an individual person is an indicator of many physiological conditions related to the individual's level of fitness or health. Through muscle activity, weak electrical currents are generated. An EMG signal is measured from these currents in a microvolt range having a frequency range of 20 to 400 Hz. The EMG signal measurement is taken on the surface of the individual using electrodes of a certain impedance.
Many examples of how EMG signal measurement correlates to health and fitness conditions involve repetitive motions including such activities as typing or manufacturing assembly with repetitive motion involving wrists, hands, arms, and shoulders. These repetitive motions may all cause health problems if done improperly. Studies have shown that those that properly undertake repetitive motion take brief rests that are oftentimes unnoticeable to the trained eye. Fortunately, activity with repetitive motion interrupted by brief rests has corresponding surface EMG activity with recognizable patterns related to signal strength versus time measurements. Attempts have been made to use these patterns to train individuals to properly practice repetitive motions to either unlearn or avoid improper habits. The effectiveness of prior art systems unfortunately has been limited due to restrictions imposed by these systems. For instance, users are restricted to certain locations and activities by the prior art systems. Also, the devices and methods providing feedback to users are cumbersome and indirect so that the prior art systems do not provide the type of demonstrative and meaningful feedback to dramatically encourage positive changes in behavior by the users.
Posture is another area in which surface EMG activity has been used with limited success to help correct conditions. Those with proper posture have certain surface EMG activity patterns at certain locations on the surface of their body, whereas those with improper posture have other patterns at the same locations. The limited success again has been due to prior art systems. The effort required to use prior art systems is as great or greater than that required to modify behavior. Oftentimes, the extra burden is too much for a user to reach desired goals and health benefits. Other situations conductive to surface EMG activity monitoring involve bruxism. Here an individual grinds their teeth while sleeping so has little awareness by natural means of the problem while it is occurring. Headaches, neck and shoulder pain, back pain, and other states of inappropriate muscle activation causing pain or muscle problem are also candidates for monitoring surface EMG activity.
Prior art devices which monitor surface EMG activity and provide feedback place unnecessary demands on users and furnish inadequate feedback. Typically, an individual being monitored by a prior art device will go to a clinic or other location such as their home where an EMG feedback monitor is located. For instance, U.S. Pat. Nos. 5,291,902 and 5,411,548 to Carmen teach methods for incontinence treatment and treatment of other health conditions. The methods are practiced in designated exercise sessions limited typically to a location in the home. The limited accessibility of prior art EMG feedback monitors affords little opportunity for training. Also, the feedback used is only indirectly associated with the regions of concern on the user's body, so is of limited value.